Electrode actuating mechanism for hot upsetting machines



July 23, 1957 H. H. HANSEN ET AL ELECTRODE ACTUATING MECHANISM FOR HOT UPSETTING MACHINES Filed Aug. 15. 1955- 4 Sheets-Sheet l INVENTORS HANS H. HANSEN ROY W. PEARSON BY I ATT

4 Sheets-Sheet 2 H. HwHANSEN ETAL INVENTORS f ATI'O EY HANS H. HANSEN ROY W. PEARSON 3 3% v wm Q v m P a S AM w. v I t 1! I n I mm m a n. a

mw mi 3 July 23, 1957 ELECTRODE ACTUATING MECHANISM FOR HOT UPSETTING MACHINES Filed Aug. 15, 1955 y 1957 1-1. 1-1. HANSEN ETAL 2,800,572

ELECTRODE ACTUATING MECHANISM FOR HOT UPSETTING MACHINES Filed Aug. 15, 1955 4 Sheets-Sheet a 11o- 113 111*"1 114 p nz INVENTORS' HANS H. HANSEN ROY W. PEARSON BY Zww f I ATTORYEY ELECTRODE ACTUATING MECHANISM FOR HOT UPSETTINGMACHINES Filed Aug. 15, 1955 July 23, 1957 H. H. HANSEN ETAL 4 Sheets-Sheet 4 hlllll Ill INVENTOR'S HANS H. HANSEN ROY w. PEARSON A O EY United States Patent ELECTRODE ACTUATING MECHANISM FOR HOT UPSETTING MACHINES Hans H. Hansen, Cortland, and Roy W. Pearson, Warren, Ohio, assignors to The Taylor-Winfield Corporation, a corporation of Ohio Application August 15, 1955, Serial No. 528,174

Claims. (Cl. 219-151) The present invention relates to the metal working and forming art, and more particularly to an apparatus for the electric resistance heating and hot forming of metal workpieces into desired shapes and sizes.

In the production of valve members for internal combustion engines, and of other parts having a generally small shank or stem portion with a bulbous section of material at some point along such stem, it has been common practice to employ hot upsetting methods, wherein a workpiece of relatively small cross section is heated through a localized area to the point of plasticity, whereupon pressure is applied to the ends of the workpiece to upset-or gather a large bulb-like quantity of material conforming somewhat in shape and size to the desired end product. This procedure is often preferred over forging operations, for example, as being faster, simpler, more economical, and productive of superior results.

Generally, in hot upsetting operations, a desired area of the workpiece is heated by bringing current carrying electrode members into contact therewith and passing a high amperage current through the desired localized area whereby the same becomes resistance heated to a plastic condition. As pressure is applied between the ends of the workpiece, material flows into and gathers within the "area between the electrodes. The shape and size of the bulb of gathered material may be varied by controlling the rate of flow of heating current, the application of upsetting pressure, and by adjusting the position of the current carrying electrodes.

All of the above is well known, generally, in the art. However, insofar as we are aware, most apparatus heretofore devised for carrying out hot upsetting operations has been of a more or less limited nature, capable of only low rates of production, and in most cases requiring the close personal attention and supervision of the machine operator. It is therefore the primary object of this invention to provide an apparatus of an improved nature which is adapted for carrying out repetitive hot upsetting operations in a substantially automatic manner and with a minimum of operator attention.

In this respect, the apparatus of our present invention embodies many of the features disclosed and claimed in our prior co-pending application Ser. No. 479,903, now U. S. Patent No. 2,768,282, filed January 5, 1955, for Apparatus for the Hot Upsetting of Metal Workpieces. However, as will become apparent, the present apparatus incorporates certain improved features which form the basis for this application.

Thus, it is an object of the invention to provide a hot upsetting apparatus of the general type set forth in our above identified co-pending application wherein there is provided a novel and improved arrangement for actuating the current carrying electrodes during hot upsetting operations and for manipulating the workpiece itself in exact accordance with the movement of the electrodes.

In the forming of valve members, for example, we prefer to provide a fixed or anvil electrode which is engaged by one end of the workpiece. A second electrode is provided which has slidable engagement with the workplece at some point intermediate its ends, generally adjacent the electrode abutting end. In addition, pusher or feeder meansis provided which acts upon the opposite end of the workpiece to forcibly urge the same toward the anvil or abutment electrode. When heating current is applied, the portion of the workpiece between the electrodes softens, and under the force of the pusher means the workpiece is moved toward the anvil electrode, as the softened forward portion of the workpiece expands and gathers into a bulb-like mass between the electrodes.

In order to properly control the size and shape of the gathering bulbous mass of softened metal it has been found desirable during the forming operation to retract the second electrode away from the anvil electrode. In accordance with the teachings of our prior co-pending application it is desirable to retract the movable electrode at an accurately controllable variable rate so that the size and shape of the gathered bulb of metal may conform as nearly as possible to that of the desired finished prodnot. And in accordance with the teachings of our present invention we not only provide for an accurate variable retraction of the movable electrode, but further provide that such retracting movement be positively and directly related to movements of the pusher element so that at all times there is an exact and positive relation between the retracting movements of the movable electrode and the quantity of metal gathering between the electrodes.

A more'specific object of the invention resides in the provision of a hot upsetting apparatus of the type having a retractible electrode and pusher means for feeding a workpiece toward a fixed or anvil electrode which has a novel combined actuating system for the pusher means and movable electrode whereby these last mentioned members may be actuated in a definite positive relation to each other, even through the movement of one member with respect to the other may vary continuously throughout an upsetting operation.

Yet another object of the invention is the provision in a hot upsetting apparatus for forming valve members and similar parts of an improved apparatus for feeding workpieces into operating position, in alignment with the electrodes and pusher means of the apparatus.

The above and other objects and advantages of the invention will become more fully apparent upon consideration of the following detailed specification and accompanying drawing wherein is disclosed a certain preferred embodiment of the invention.

In the drawing:

Figure 1 is a side elevation of a hot upsetting apparatus constructed in accordance with the teachings of our invention;

Figure 2 is an enlarged fragmentary section view taken generally along line 2-2 of Figure 1;

Figure 3 is an enlarged fragmentary view of the electrode members of our apparatus, illustrating the manner in which a workpiece is engaged thereby;

Figure 4 is a side elevation of another embodiment of our invention; and

Figure 5 is a section view taken 5-5 of Figure 4.

Referring now to the drawing, the numeral 10 designates generally the main frame structure of our apparatus, which is comprised of a plurality of welded iron or steel structural members 11. Mounted on the framework 10, near the upper end thereof, is a transformer 12 which is of a type commonly employed in electric resistance welding, for example, having a low voltage-high amperage secondary winding.

Rigidly secured to the front face of the frame 10, adjacent the top portion thereof, is a support 13, upon generally along line which is mounted, by means of a current conductive auxiliary bracket 14, a fixed or anvil electrode member having a downwardly facing contact surface 16.

One of the terminals 17 of the transformer 12 is connected through a heavy conductor 18 with the conductive bracket 19, and hence with the anvil electrode member 15.

Positioned below the'anvil electrode 15, in axial alignment therewith is a feeder device 19, to be described in more detail, in which is provided a vertically disposed grooved and slotted workpiece holder 20 which is arranged to slidably receive and support a rod-like workpiece 21.

Aligned with the workpiece holder 20, and positioned generally below the same, is a pusher mechanism 22 comprising a' fiat vertically disposed blade 23 which is received within the slotted workpiece holder 20, a slide member 24 upon which the blade 23 is mounted, and an actuating cylinder 25 which connects the slide 24. The

cylinder 25 is mounted on the frame 10 by means of an outwardly extending support 26, so that upon proper energization the slide 24 and blade 23 carried thereby maybe caused to move vertically in upward or downward directions.

In general accordance with the teachings of our before mentioned prior co-pending application there is provided between the lower contact surface 16 of the anvil electrode 15 and the upper end of the workpiece holder 20 a second and movable electrode assembly 27. As shown in more detail in Figure 2, the electrode assembly 27 comprises a pair of opposed electrode members 28 and 29 which are mounted on pivoted electrode carriers 30 and 31. The carriers 30 and 31 are pivoted at 32 upon alcarriage member 33, and are moved in opening and closing directions by means of links 3537 and a hydraulic actuator 33 which is also mounted upon the carriage 33.

Mounted adjacent the upper and lower ends of the carriage-33 are pairs of anti-friction rollers 39 and 40 which are angularly related with respect to each other and which are adapted to engage angularly related bearing surfaces 41 and 42. The arrangement is such that the carriage 33 is rigidly supported and guided, While being anti-frictionally movable in vertical directions over a limited traverse, as defined by bearing blocks 43.

As will be observed in Figure 2, for example, the bearing blocks 43 are rigidly mounted upon the frame by means of U-shaped brackets 44.

Referring again to Figure 2, it will be observed that the electrode carriers 30 and 31 are provided with integral outwardly extending current conductive arms 45 and 46 to which are attached flexible conductors 47. The flexible conductors 47 are in turn connected to busses 48, leading to the second terminal 49 of the power transformer 12.

It will thus be apparent that in the assembled apparatus the anvil electrodes 15 and 27 constitute opposite terminals of a power source, so that when these electrodes are in contact with a workpiece a circuit is completed in which the workpiece constitutes a resistance member, to be heated by the flow of current.

During an upsetting operation, while the upper end portion of a workpiece 21 is heated by the flow of current between electrodes 27 and 15 pressure is applied to the lower end of the workpiece by means of the pusher blade 23, which is acted upon by the hydraulic actuator 25. The heated end portion is thereby caused to deform and the lower portion of the rod-like workpiece moves upwardly, sliding through the then closed or clamped electrode members 28 and 29. As the operation progresses an increasing bulb of soft metal gathers between the electrodes 15 and 27, so that it becomes desirable to retract the electrode assembly 27 downwardly, away from the anvil electrode 15.

Thus, in accordance with the teachings of our present invention the slide member 24, interconnecting the pusher blade 23 and actuating cylinder 25 therefor, is provided along its inner side with a series of gear teeth 50, forming a rack portion, which are arranged to mesh with a pinion 51. The pinion 51 is journaled on a shaft 52 which is mounted on the support 26, in fixed relation to the machine frame 10. The arrangement is such that upon upward or downward movement of the slide 24, in response to appropriate energization of the actuator 25, the pinion 51 rotates about the shaft 52.

Secured to and carried in rotary movements by the pinion 51 is a cam 53. Engaging the upper surface of the cam 53 is a follower wheel 54 which is carried by a bracket 55 depending integrally from the electrode carriage 33.

At the upper end of the electrode carriage 33 there is provided a coil spring 56 which acts downwardly against the carriage 33 and upwardly against the electrode support 13. The spring 56 thus maintains the follower wheel 54 in firm contact with the cam 53.

Thus, during the progress of an upsetting operation, as the slide 24 and pusher blade 23 move upwardly in response to the heating of the workpiece 31 and the gathering of the upper portion thereof into a bulb-like mass between the electrodes 15 and 27, the pinion 51 and cam 53 are rotated in exact accordance with the upward movement of the blade 23. In the View shown in Figure l, the cam 53 will rotate in a clockwise direction. The area of the cam designated in Figure 1 as 53a, which is the highest portion of the cam, that is, the portion with the largest radius, is at the top at the beginning of an upsetting operation. In this position the carriage 33 and the electrode assembly 27 are in their uppermost positions. Then, as the blade 23 moves upwardly, causing the cam 53 to be rotated, lower or lesser radiused portions of the cam move underneath the follower wheel 54, in response to which the carriage is moved downwardly by means of the spring 56.

Since the rotation of the cam is directly related to the movement of the blade 23, and hence with the deformation of the workpiece, the retraction of the movable electrode assembly 27 is at all times directly and accurately related to the condition of the workpiece. Moreover, since the size and shape of the bulbous gathering of heated metal between the electrodes 15 and 27 is in a large measure controlled by the retracting movements of the movable electrode assembly 27, it is possible by appropriately contouring the active outer surface portions of the cam 53 to accurately regulate the form of the final product. And in this respect, it will be understood that the invention contemplates the interchanging of earns 53 where necessary or desirable to obtain finished products of various shapes and sizes.

In order to facilitate the loading and unloading of workpieces into and out of working position we have provided an improved feeder device 19 comprising a rotary turret 57 upon which are mounted a plurality of circumferentially spaced vertically disposed workpiece holders 2%. Each of the holders 20 has a vertically disposed radially outwardly opening slot 53 therein which is arranged to slidably receive and guide the pusher blade 23, substantially in the manner indicated in Figure l. The opposite side walls of the slots 58 are provided with complementary grooves 59 in which are slidablyreceived the rod-like workpieces 21.

At the bottom of each of the workpiece holders 20 there is provided an abutment plate 60 which is slotted but not grooved so as to permit the blade 23 to pass therethrough, while forming an abutment surface against which the lower ends of the workpieces 21 may rest.

Adjacent and above the outer side of the turret 57 is a loading hopper 61 which is arranged to feed workpieces, one at a time, into the upper ends of the grooved slots 58. Then, in a step-by-step manner, the turret rotates, bringing each workpiece into alignment with the electrodes 15 and 27 and with the pusher blade 23. The operation is thus 'rendered more or'less continuous in nature, capable of high production rates, and requiring a minimum of operator attention.

Referring now to Figures 4 and 5, illustrating a second embodiment of our invention, the reference numeral 100 represents a frame structure upon which is supported a fixed anvil electrode 101 and movable carrier 102 mounting electrodes 103. The electrodes 101 and 103 are connected to the terminals of transformer 104.

Below the anvil electrode 101 is a workpiece guide 105,

forming part of feeder mechanism 106, as heretofore described. A pusher blade 107 is carried by a slide 108 and is received in the guide 105. I As shown in Figure the slide 108 has a rack 109 mounted on the inner side thereof and adapted for engagement with a pinion 110 journaled in the frame 100. On the end of the pinion journaling shaft 111 is a removable cam 112 which rotates with the pinion 110.

Pivotally mounted on the frame 100, adjacent the cam 112, is a lever 113, upon the outer end of which is journaled a follower wheel 114 which engages the contoured outer surface of the cam 112. Adjacent its inner end the lever 113 connects pivotally with a draw bar or link 115 which in turn is connected to the movable electrode mounting carriage 102. Also connected to the inner end of the lever 113 is the operating rod 116 of an air cylinder 117. The cylinder 117 is positioned below the lever 113 and is attached to the frame 100 by means of a cross brace 118.

In accordance with the preferred teachings of the invention the cylinder 117 connects with a suitable air supply, not shown, which is normally directed into the lower or head end of the cylinder. Thus, there is continually exerted upon the rod 116, and hence the inner end of the lever 113 a resilient upward force. This supports the weight of the electrode carriage 104 and also causes the follower wheel 114 to be pressed into firm engagement with the cam 112. Thus, during an upsetting operation, as the cam 112 is rotated by the upward movement of the slide 108, the follower Wheel is urged upwardly, causing the lever 113 to pivot in a clockwise direction, against the resilient restraining force of the cylinder 117. In this manner the electrode carriage is retracted downwardly from the anvil electrode 101 in a smooth and precise manner which is productive of superior operating results.

At the end of an upsetting operation there is a large bulb-like gathering of metal at the anvil electrode 101 which often tends to adhere to the surface of the electrode. Thus, in accordance with the teachings of the invention the cylinder 117 is reversely actuated at this time, that is, the air pressure is supplied to the upper or rod end of the cylinder. This causes the lever 113 and carriage 102 to be drawn forcibly downward, freeing the workpiece and retracting the same slightly from the anvil electrode so that the rotary feeder mechanism 106 may be operated to remove the finished workpiece while moving a new piece into upsetting position.

Of course, the carriage 102 need not be retracted any substantial distance to properly free the workpiece from the anvil electrode 101, a small fraction of an inch generally being suflicient. Therefore, we provide a limit stop means comprising a removable abutment block 119 and a stop arm 120 which is carried by the lever 113. After a predetermined clockwise movement of the lever 113, sufficient to free a finished workpiece after an upsetting operation, the stop arm 120 engages the abutment block 119 so that further movement of the lever 113 and carriage 104 is prevented,

In Figure 4 we have illustrated the workpiece feeder mechanism 106 in somewhat more detail than in Figures 1 and. 2, and, it will be observed that the rotary carrier 121 is supported upon a platform 122 which is connected to a hydraulic cylinder 123. The cylinder 123 is periodically energized to move the rotary carrier 121 toward and away from the upsetting machine and from the loading station 124.

Other details of the loading mechanism form no part of the present invention, and further detailed description thereof will be omitted.

It should thus be readily apparent that we have accomplished the several objects initially set forth. We have provided an improved hot upsetting apparatus for forming valve members and similar parts which incorporates many of the advantageous teachings of our prior co-pending application Serial No. 479,903, while providing for several important improvements over our prior apparatus.

Perhaps the most important single improvement in our present apparatus resides in the provision of a combined actuating system for the workpiece pusher and movable electrode assembly whereby the movable electrodes may be retracted in exact and predetermined relation to the deformation of the workpiece as the upsetting operation proceeds. Moreover, we provide for an accurate and controllable regulation of the size and shape of the finished product through appropriate contouring of the cam member which forms part of the combined actuating system.

In respect of the above, We wish to acknowledge that it has been broadly suggested heretofore, in U. S. Patent 1,772,444, to Giacchino, for example, that the movement of the pusher member be mechanically interconnected with retractible electrode members in a hot upsetting apparatus. However, our present invention is directed to improved arrangements for carrying out the operation in a practical and versatile manner.

Another important feature of the invention resides in our improved feeder mechanism which incorporates a plurality of slotted and grooved workpiece holding members mounted upon a turret member which is adapted to bring new workpieces into operative position within the upsetting machine in a rapid and expeditious manner so that a high rate of production may be realized.

It should be understood, however, that the specific embodiment herein disclosed is intended to be illustrative only, as many changes may be made therein without departing materially from the teachings of the invention. Reference should therefore be made to the following appended claims in determining the full scope of the invention.

We claim:

1. In an apparatus for hot upsetting metal workpieces including a frame, electrode members for engaging a workpiece at spaced points, means to supply current to said electrodes, means movable along the principal axis of said apparatus in a first direction for applying pressure to said workpiece to cause a deformation thereof between said electrodes, and means to move one of said electrode members along said axis in a second direction; the improvement in said means to move comprising yieldable means tending to urge said one of said electrode members in said second direction, cam means operative to urge said one of said electrode members in said first direction against the action of said yieldable means, and means mechanically interconnecting said cam means and said means for applying pressure whereby movement of one cause a direct and related movement of the other.

2. Apparatusaccording to claim 1 wherein said means for applying pressure comprises a pusher blade, a slide mounting said pusher blade, and a fluid actuator for said slide and pusher blade, and said means mechanically interconnecting said cam means and said means for applying pressure comprises a rack portion on said slide member and a pinion gear meshing with said rack portion.

3. In an apparatus for hot upsetting metal workpieces including a frame, electrode members for engaging a workpiece at spaced points, means to supply current to said electrodes, means movable along the principal axis of said apparatus in a first direction for applying pressure to said workpiece to cause a deformation thereof between said electrodes, and means to move one of said electrode members along said axis in a second direction, the improvement in said means to move comprising a cam member adapted upon movement thereof to cause a predetermined but varying retracting movement of said one of said electrode members, and means directly and mechanically interconnecting said cam means and said means to apply pressure whereby upon movement of said last mentioned means said cam means is moved correspondingly.

4. In an apparatus for hot upsetting metal workpieces including a frame, a fixed anvil electrode, movable electrode means, workpiece pushing means aligned with said anvil electrode and adapted to exert a pushing force upon a workpiece held in said electrode means and in abutting relation with said anvil electrode, and means to retract said electrode means from said anvil electrode during an upsetting operation, the improvement in said pushing means and means to retract comprising a rotary cam member, yieldable means retaining said electrode means in engagement with said cam member, and means i interconnecting said cam member and pushing means whereby upon pushing movement of said latter means said cam member is caused to rotate to cause a predetermined but varying retracting movement of said electrode means.

5. In an apparatus for hot upsetting metal workpieces including a frame, a fixed anvil electrode, movable electrode means, workpiece pushing means aligned with said anvil electrode and adapted to exert a pushing force upon a workpiece held in said electrode means and in abutting relation with said anvil electrode, and means to retract said electrode means from said anvil electrode during an upsetting operation, the improvement in said pushing means and said means to retract comprising a rotary cam member adapted upon movement thereof to cause a retracting movement of said electrode means, a slide member forming part of said pushing means and having a rack portion, and means engaging said rack portion and connecting said cam member for moving said cam member in direct response to movements of said slide.

6. In a hot upsetting apparatus the combination of a fixed anvil electrode, workpiece holding means for holding a workpiece in alignment with said anvil electrode, said workpiece holding means having a longitudinal slot therein, a pusher blade received in said slot, retractible electrode means adapted to engage a workpiece between said workpiece holding means and said anvil electrode, means to move said pusher blade in a longitudinal direction toward said anvil electrode, said retractible electrode means including a carriage adapted for longitudinal movement in a plane parallel to said pusher blade and away from said anvil electrode, and cam means rotated by movement of said pusher blade and operative to cause said carriage to move at a predetermined variable rate in relation to the movements of said pusher blade.

7. Apparatus according to claim 6 further characterized by said cam means including a pinion gear, and gear means associated with said pusher blade and meshing with said pinion gear to positively drive the latter in direct relation to movements of said pusher blade.

8. Apparatus according to claim 7 further characterized by said cam means tending to urge said carriage in one direction and further including yieldable means tending to urge said carriage in the opposite direction.

9. In a hot upsetting apparatus of the type having a pair of spaced electrodes adapted to engage a rod-like workpiece, pusher means for acting upon said workpiece during an upsetting operation, means to hold the workpiece during an upsetting operation and means to feed new workpieces into upsetting position, the improvement in said means to hold and means to feed comprising a turret member, a plurality of longitudinally disposed workpiece holding members mounted in circumferentially spaced relation about said turret, said holding members having slots therein for the reception of said pusher means and having grooves in said slots for the reception 8 of said workpieces, abutment means at one end of each of said workpiece holding members, said abutment means having slots therein for the reception of said pusher means and acting to close off said grooves at said one end, and means positioned in spaced relation to said electrodes for feeding workpieces into said grooves.

10. In a hot upsetting apparatus of the type having a pair of spaced electrodes adapted to engage a rodlike workpiece, pusher means for acting upon said workpiece during an upsetting operation, means to hold the workpiece during an upsetting operation, and means to feed new workpieces into upsetting position, the improvement in said means to hold and means to feed comprising a turret member, a plurality of longitudinally disposed workpiece holding members mounted in circumferentially spaced relation about said turret, said workpiece holding members having longitudinal openings therein for the reception of said pusher means and said workpieces, means spaced outwardly of said electrodes for feeding workpieces into said openings, and means adjacent one end of said workpiece holding members for engaging the ends of said workpieces.

ll. In a hot upsetting apparatus the combination of a fixed anvil electrode, workpiece holding means for holding a workpiece in alignment with said anvil electrode, said workpiece holding means having a longitudinal opening therein, a pusher member received in said opening, retractible electrode means adapted to engage a workpiece between said workpiece holding means and said anvil electrode, means to move said pusher member in a longitudinal direction toward said anvil electrode, said retractible electrode means including a carriage adapted for longitudinal movement away from said anvil electrode, including a cam rotated in direct relation to the movement of said pusher member and operative to cause said carriage to move at a predetermined variable rate in relation to the movement of said pusher member.

12. Apparatus according to claim 11 further characterized by said last mentioned means including a fluid cylinder acting upon said carriage in opposition to said cam.

13. Apparatus according to claim 11 further characterized by said last mentioned means including a pivotally movable lever, a follower wheel carried by said lever and engaging said cam, and means interconnecting said lever and said carriage.

14. Apparatus according to claim 13 further including yieldable means acting upon said lever to urge said follower wheel toward said cam.

15. Apparatus according to claim 14 further characterized by said yieldable means comprising a fluid cylinder normally urging said carriage toward said anvil electrode but adapted upon reverse actuation thereof to draw said carriage forcibly away from said anvil electrode.

16. Apparatus according to claim 15 further including abutment means associated with said carriage and adapted to limit movement thereof in a direction away from said anvil electrode.

17. In a hot upsetting apparatus of the type having a pair of spaced electrodes adapted to engage a rod-like workpiece, pusher means for acting upon the workpiece during an upsetting operation, means to hold the workpiece during an upsetting operation, and means to feed new workpieces into upsetting position, the improvement in said means to hold and said means to feed comprising a movable member, a plurality of longitudinally disposed workpiece holding members mounted in spaced relation on said movable member, said workpiece holding members having longitudinal openings therein for the reception of said pusher means and the workpieces, means spaced outwardly of said electrodes for feeding workpieces intosaid openings, and means 9 adjacent said workpiece holding members for engaging said workpieces.

18. In an apparatus for hot upsetting metal work-, pieces of the type having first and second electrode means, said first electrode means being adapted to releasably grip a workpiece intermediate its ends, means movable along the principal axis of said first electrode in a first direction for applying pressure to said workpiece to cause a deformation thereof between said electrodes, and means to move said first electrode along said axis in a second direction; the improvement in said means to move and said first electrode comprising yieldable means tending to urge said first of said electrode means in said second direction, means operative to urge said first of said electrode means in said first direction against the action of said yieldable means, said first electrode means comprising a pair of electrode supporting arms mounted for pivoting movement, electrodes carried at the free end portions of said arms adapted upon pivoting movement to move toward or away from said axis, a fluid cylinder for pivoting said arms for opening and closing said electrodes, and actuating linkage interconnecting said arms and the operating rod of said fluid cylinder.

19. In an apparatus for hot upsetting metal workpieces including a frame, electrode means for engaging a Work piece at spaced points, means to supply current to said electrodes, means movable along the principal axis of said apparatus in a first direction for vapplying pressure to the workpiece to cause the deformation thereof between said electrodes, and means to move one of said electrode members along said axis in a second direction; the improvement in said last mentioned means comprising yieldable means tending to urge said one of said electrode means in said second direction, means operative to urge said one of said electrode means in said first direction against the action of said yieldable means, an electrode mounting carriage positioned in offset relation to said axis and movable in parallel relation thereto, said carriage carrying said one of said electrode means, and means mounting said carriage to said frame including a plurality of anti-friction rollers.

20. Apparatus according to claim 19 further characterized in that said first electrode means further comprises a pair of electrode supporting arms mounted for pivoting movement on said carriage, electrodes carried on the free end portions of said arms adapted upon pivoting movement of said arms to move toward and away from said axis, a fluid cylinder for pivoting said arms for 1O opening and closing said electrodes, and actuating linkage interconnecting said arms and the operating rod of said fluid cylinder.

21. Apparatus according to claim 19 further characterized in that said means operative to urge said one of said electrode means in said first direction against the action on said yieldable means and said means movable for applying pressure to the workpiece are mechanically interconnected whereby movement of one of these last mentioned means causes a direct and related movement of the other.

22. Apparatus according to claim 19 further characterized in that said means operative to urge comprises a cam rotated in direct relationto the movement of said means movable for applying pressure to the workpiece, and said yieldable means comprises a fluid cylinder acting on said carriage in opposition to said cam.

23. In a hot upsetting apparatus the combination of an anvil electrode, workpiece holding means for holding a workpiece in alignment with said anvil electrode, means movable along the principal axis of said anvil electrode for applying pressure to said workpiece to cause a deformation thereof, retractable work piece engaging means adapted to engage the workpiece intermediate the ends thereof, said retractable electrode means comprising a carriage adapted for movement away from said anvil electrode, mechanical means interconnecting said carriage and said movable means for applying pressure whereby movement of one of these causes a direct and related movement of the other, said mechanical means comprising a cam, and a fiuid cylinder acting upon said carriage in opposition to said cam.

24. Apparatus according to claim 23 further characterized in that said fluid cylinder normally urges said carriage toward said anvil electrode but adapted upon reverse actuation thereof to draw said carriage forcibly away from said anvil electrode.

25. Apparatus according to claim 23 further including abutment means associated with said carriage and adapted to limit movement thereof in a direction away from said anvil electrode.

References Cited in the file of this patent UNITED STATES PATENTS 1,772,444 Giacchino Aug. 5, 1930 1,870,987 Drake Aug. 9, 1932 FOREIGN PATENTS 723,461 Great Britain Feb. 9, 1955 

